Heretofore, cell cultures have frequently been carried out in the field of medicine, pharmacology, biology, etc., in order to multiply or sustain cells separated from multicellular organisms in an in vitro environment.
As a typical example of cell cultures, there may be mentioned a cell culture, a so-called adhesion culture, which is involved in placing a liquid culture medium in an incubator with a thin film formed on its inner bottom with a biocompatible material or the like, and inoculating cells on the liquid culture medium, followed by incubating the cells on the thin film that is used as a scaffold.
The cells inoculated in the manner as described above may multiply by means of cell division and expand on the scaffold, resulting in the formation of a layer of the cells.
The cells multiplied as above in the film form are required to be detached from the scaffold in the incubator in order to allow a further use for experiments or another culture.
The cultured cells attached to the scaffold with a comparably weak adhesion force, on the one hand, may be detached from the scaffold by physically scratching an cultured cells off the scaffold with a tool called a scraper. The cultured cells attached thereto with a comparably strong adhesion force, on the other hand, have conventionally been detached from the scaffold by decomposing an adhesion factor between adhered cells and the scaffold with a protease including, for example, collagenase or trypsin.
The detachment method using the protease, however, may encounter difficulties in decomposing the adhesion factor upon detachment of the adhered cells from the scaffold because the protease may involve the risk of decomposing and destructing proteins other than the adhesion factor, such as membrane proteins, which are present on the cell surfaces.
Therefore, a method that does not require the use of the protease has been proposed, which is involved in the detachment of cells attached to a scaffold by delivering an ultrasonic vibration to an incubator from upwards (for example, see Patent Document No. 1).
The method using the ultrasonic vibration is reported as capable of detaching the adhered cells from the scaffold without destroying proteins such as membrane proteins on the surfaces of the cells.